Heating apparatus



May 15, 1945.

M. L. MUELLER HEATING APPARATUS Filed. Jan. 15, 1941 2 Sheets-Sheet 1 rlilnnl e0 INVENTOR. flan)? //Ye//9r- Patented'May15, 1945 lfiidild UN MED STATES PATEN E @F 2,376,179

mauve arrana'rus Moritz L. Mueller, Grosse Pointe, Weir. Application January 15, 1941, Serial No. 374,522

25 Claims.

This invention in general relates to heating apparatus-and has particular reference to a novel and improved apparatus for efiiciently burning fueloand recovering heat from the flue ases.

as illustrated in the embodiment of themvention selected for purposes of illustration, one

. covering heat from the flue gases therefrom;

change device having a passageway for flue gases therethrough, one end of said passageway being connected to the flue gas ou et from said space heater and the other end of said passageway being connected to a conduit leading to a vent,

stack or chimney, a damper controlled by-pass between said outlet and said conduit and adapted when open for shunting said radiator out of the path of travel of said flue gases and so as to permit natural draft of the gasesof combustion through said space heater, outlet therefrom and conduit to said vent, forced draft efiectin means in said passageway operable for closing said bypass and for effecting a forced draft through the space heater, burner, burner outlet and the radiator of the flue gases to the vent, means associated with the manually regulatable oil supplying means for rendering said forced draft effecting means operative and inoperative and means associated with said forced draft effecting means and operative therewith for circulating a. medium to be heated in heat exchangerelationship with said radiator.

Principal objects of the invention are:

To provide in combination with a heating element, an economizer which can be rendered operative and inoperative in accordance with variations in the heat output of and/or the fuel input to said heating element;

, To provide in'combi'nation with a. forced draft eifecting means for a combustion burner, a means to provide natural draft operation of the. burner when the forced draft effecting means are inoperative; 4

To provide an accessory device in the nature of an economizer and forced draft creating and air circulating means for use in connection with:

space heaters and other forms of heating appliances now already in use for materially increas-- in; the utility and efllciency thereof;

To provide a so-called space heater construction which is more eincient and dependable in operation and more useful than heaters of this kind which are now available; 7

To provide in combination with an atmospheric oil burner, a means for aiding combustion and recovering a higher percentage of the heat from the combustion gases therefrom;

To provide a heating device having a combustion burner with a plurality of heat exchange elements through which the flue gases oi combustion circulate, with means for rendering one of said elements operative and inoperative by bypassing the flue gase therearound and in accordance with the heat output of the burner.

- Other objects and advantages of the invention will be apparent from a consideration of the following specification taken in conjunction with the accompanying drawings, of which there are two sheets, and wherein:

Fig. l is a, vertical sectional view through an economizer unit embodying a part of my invention;

Fig. '2 is a section taken-along the line 2-2 of Fig. 1, looking in the direction of the arrows and showing the construction of the flue gas blower;

Fig. 3 is a section taken in the plane along line 33 of Fig. 1, looking in the direction of the arrows and showing further details of construction of the damper controlled by-pass;

Fig. 4 is a horizontal section taken along the 7 line 4-4 of Fig. l; h

Fig. 5 is a somewhat diagrammatic view illustrating, partly in section, the combination of an economizer embodying my invention with a space heater having an atmospheric or heat vaporizing typ oil burner;

' Fig. 6 is a view illustrating diagr' ammatically another type of arrangement of an economiz er embodying my invention in combine tion with a. space heater; and

Fig 7 isan enlarged viewillustratingrmeform er indicated generally at E8. The burner l8 comprises a baflle 20 arranged transversely of the drum it and provided with a central opening 24, A pot'zii having a series of air intake openings 2% provided in the walls thereof is arranged below the bafie 2d and communicates with combustion chamber it through the opening 24 therein. Air

to support combustion in the pct 26 at low fire and in the pct Ed and combustion chamber 96 at high'fire is admitted into the drum it through a fixed opening therein. Oil is supplied to the bottom of the pot Eiifrom a fuel supplying and regulating means which comprises an oil reservoir $2, a conduit 34 leading from, the reservoirto a regulatable flow controlling device 36 and a conduit 38 communicating at one end thereof with the device 36 and at the other end thereof with the bottom ofv the burner pot 26 supplies regulated quantities of oil to the burner.

The device '36 includes a manual control comprising a rod 50, a dial 42 and an indicator 44 (Fig. 7) by means of which the device 36 may be set to supply oil in desired quantities to the burner E8 so as to obtain either low, intermediate. or high fire within the combustion chamber i5.

The oil in the bottom of the pot 26 may be ignited by manually applying a light or flame.

thereto through the door 46. The heater body i4 may be arranged within a casing 48, and air to be heated will circulate by. gravity over the outside surface of the heater body l4 and absorb heat from the body M which in turn is heated by the gases of combustion or flue gases in the combustion chamber i6.

The casing 48 may be open at the top, sides,

. and bottom so as'to expedite the circulation of air in heat exchange relationship therewith. The

- heater body it is provided-with a flue gas outlet 59 which is connected with the economizer ID in such a way as to supply flue gases to the intake side thereof. While the construction of the econ- 'omizer and the arrangement thereof in relationship to the body 14 of the space heater is illustrated in Fig. 5, reference may now be had to Fig. 1 for a more complete illustration of .the

construction of the economizer In which, as illustrated, consists of an outer casing 52 having an inner casing 54 arranged therein and in spaced relationship with respect to the outer casing 52. The outer casing 52 as illustrated is rectangular 'in cross-section and is provided with an air intake 56 at the bottom on one side thereof and with a hot. air discharge 58 at the bottom on the opposite side thereof. The outer casing 52 may 'be mounted upon a base 50 in such a manner as to permit vertical adjustment of the casing 52 with respect to the base 60. v

The innercasing 54 which comprises a radiator or heat exchange element may be of rectangular shape, as illustrated in Fig. 4, and is supported within the casing 52 in such a manner as to permit circulation of air within the casing 52 over substantially all of the outside surface of the casing 54 as is explained more fully hereafter. The inside of the casing or radiator 54 is divided by a vertically arranged partition 6| extending transversely of the casing 54 so as to provide a duct or passageway 62 thereof on one side and id. The flue gas blower may, as illustrated (Fi '2),, be of the blower wheel type of pressure fan through the passageway 64. The upper end of the passageway 54 is connected by a sleeve lit to a conduit means ill] which leads to a chimney or vent for the flue gases, the same being forced through the chimney or vent by the blower to.

To facilitate following the path of travel of the flue gases through the economizer, such path has been indicated by dotted arrows while the path of the air to be heated and which circulates over the outside of the radiator ad has been indicated by full line arrows.

The blower wheel 12 is mounted on a shaft til so as to be driven thereby and this shaft may form a continuation of the main shaft or" an electric motor 82 mounted upon the base tit. It

will be observed that the flue gases are drawn downwardly through the passageway 52 from the intake 65 of the economizer and are then forced upwardly through the passageway 54 to the discharge side 78 of the economizer and that the radiator 54 is arranged below the level of the outlet 50 from the heater body.

The partition Bl which divides the intake passageway 52 of the economize: from the discharge passageway 64 thereof includes a movable damper 84 which, when the blower is operating. is arranged as illustrated in full lines in Fig. l to close a by-pass or opening 86 between the intake 56 of the economizer and the discharge l8 thereof. The damper 84 (Fig. 3) comprises a plate pivotally mounted upon a rod 68 supported in the side walls of the casing 54 and the damper 84 is the damper 84 exposed to the intake passageway 62 and the pressure efiect of the flue gases discharged by the blower 10 on that portion of the damper 84 exposed to the discharge passageway 64 will move the damper 84 from the position shown in dotted lines to the full line position shown in Fig. l and will hold the damper in such position as long as the blower i0 is operating.

A screw 92 threadedly supported in a nut 94 carried by the wall of casing 54 is adapted to be advanced or retracted and is engageable with the damper 84 for limiting its counterclockwise movement so as to bleed flue gases, if desired, from the discharge passageway 64 to the intake passageway 62 for the purpose of controlling or setting the maximum forced draft provided by the blower 10.

An air circulating means comprising a blower Hill similar in construction and operation to the blower I0 and also mounted upon the shaft and arranged to be driven thereby is arranged in the lower part of the casing 52 and externally ofthe casing 54. The blower Hill is arranged to draw air through the air intake 56 and to disbracket I05 pivotally mounted at let, the end of.

charge such air upwardly on the air intake 56 side into the space between the casings 52 and 54 and downwardly on the discharge 58' side thereof and to discharge a stream of heated air laterally through the air discharge 58 of the economizer as illustrated in Figs. 1 and 5. The air discharged from the economizer may pass along the floor below the heater i l and outwardly into the room in which the space heater i2 is arranged or be directed in any other direction. The

heated air discharged from the economizer pref- I erably is arranged so as not to interfere with the gravity circulation of air over the heater body I l. In passing through the space between the casings 52 and 50 the air passes over the heated outside surfaces of the casing 54 and absorbs heat therefrom, the casing 55 being heated by the flue gases which pass through the passageways 62 and 6% thereof.

As the blowers l and I00 are driven by the same shaft, it is evident that when the blower I0 is operating to provide a circulation of flue gases through the radiator 56, that the blower I00 will operate to provide a forced circulation of air over the outside surface of the radiator d in heat exchange relationship therewith and conversely, when the blower i0 is stopped, the blower I00 will be stopped as when the blower 1c is stopped the outside surface of the casing 54 will not be heated due to the fact that the flue gases will by-pass the bracket comprising a follower shaped so as to engage a cam track HI arranged on rod to so as to rotate therewith. As illustrated in Fig. '7, the oil iiow regulating device 35 is set on No. 4 position to supply oil for a medium fire and the mercury switch 50? is tilted so that the mercury therein has closed the circuit I05. Turning the dial 52 from the position illustrated in Fig. '7 so as to increase the oil flow will not open the contacts of the mercury switch I07, but turning of the dial 412 so as to decrease the oil flow from that indicated-in 7 will cause the mercury switch 'W'l to tilt in a clockwise direction and open the contacts. Thus it will be observed-that the motor circuit is closed and opened as the fuel input to the burner is increased and decreased. As the heat output of the burner willvary in accordance with the fuel input, it will be appreciated that the economizer will be rendered operative and inopera'tlve in accordance with the vaflation in the heat output of the burner.

When the flue gas blower id is operating, the forced draft through the air intake to thepot burner and combustion chamber will assure an adequate supply ofair to support combustion and the increased heat output of the burner will be the radiator 50 and will pass directly from the outlet 5? of the heater body to the pipe or conduit 80 leading to the stack.

In addition to setting up a circulation of flue gases through the radiator 54 of the economizer the blower 10 also induces a forced draft through the air intake openings of the burner I8 and the combustion chamber I6 and thereby provides a forced draft and an increased air supply for the burner It thus insuring an efficient combustion of the oil vapors in the combustion-chamber I6.

The motor 82 is adapted to be supplied with electric energy through a circuit i0 5 which includes a switch indicated generally at I06 in Fig.

5, the construction of which is shown in 'Fig. 7.

The switch I06 is associated with the means 36 for regulating the supply of oil to the pot burner I8 and preferably is arranged so that the switch is open and the circuit I04 is open when a comparatively small amount of oil is supplied to the pot burner I8. Thus at such time that the motor circuit I04 is open'the' burner I8 is arranged to operate on a natural draft due to the stack or chimney and theproducts of combustion will pass from the. outlet 50 of the combustion chamber I6 through the by-pass 86 directly. to the pipe 00 leading to the'chimney. As the dial 42 is turned to increase the supply of oil to the pot burner I8 the switch I06 may be arranged so as to be closed thereby energizing the motor circuit I04 and starting the flue gas blower I0 and air circulating blower I00, thereby increasing the air supply to the burner along with the increase in the fuel.

a good combustible mixsupply so as to provide The switch I06 may until the supply of oil to the pot absorbed at least in part by the forced circulation of air to be heated over the radiator 5d of the economizer.

In the construction illustrated in Fig. 5 the economizer I0 is illustrated as being built into the space heater i2 and is arranged inside the cabinet 38 thereof, while in Fig. 6 a modified form of arrangement is illustrated in which the economizer Himaybe' arranged in a room I35 other than the room H38 in which the space heater i2 without the economizer therein is arranged. The

hook-up of the economizer ill in the modification illustrated in Fig. 6 to the space heater i2 is the same as that illustrated in Fig. 5 except that a length of p pe I I0 is arranged between the outlet of the space heater I2 and the intake of the economizer It so as to permit their arrangement in separate rooms, thepipe passing through an aperture in a partition H2. In this modification the air circulated over the radiator of the econom zer will heat the air in the room I05 while the air passing over the heater or heat exchange element of the space heater 5? will heat the air in the room I08. Other modifications of the arrangement of the economizer I0 with respect to the space heater I! may be provided, and alsoother types of combustion. burners and heating appliances may be used in connection with the economizer I0.

It will be appreciated that the switch I06 may be set so as to close the motor circuit I04 at any desired setting of the dial 42 so as to cut the economizer in and out of operation at any desired position of setting for the oil flow regulating device 36.

While the invention has been described with some detail, it is to be understood that the description is for the purpose of illustration only and is not definitive of the limits of the inventive idea. The right is reserved to make such changes in the details of construction and arrangement of parts as will fall within the purview of the attached claims.

I claim:

1. In combination with a space heater comprising a heat exchange element having a combustion' burner which is constructed and arranged to operate under natural draft for supplying heated flue gases thereto and an outlet for flue gases, air intake means for admitting air to said burner to support combustion, said heat exchange element being exposed to the gravity circulation of a medium to be heated thereover, an economizer comprising a radiator having a passageway for flue gases therethrough, a connection between one end of said passageway and said outlet, a conduit connected to the other end of said passageway and leading to a vent, a damper controlled lay-pass between said connection and said conduit and arranged so as to be open to permit natural draft of the flue gases from said combustion burner to said vent, means for effecting a forced draft through said combustion burner, connection, radiator and conduit to said vent and operative for closing said by-pass, and means for circulating a medium to be heated, other than that which is brought into heat exchange relationship with said heat exchange element, over said radiator when said forced draft effecting means are operative.

2. In combination with a heat exchange element having a combustion burner which is constructed and arranged to supply heated flue gases thereto under natural draft conditions for heating the same and an outlet for the flue gases, air intake means for admitting air to said burner to support combustion, a radiator arranged below the level of said outlet and having a passageway for flue gases therethrough, one end of said passageway being connected to said outlet and the other end of said passageway terminating at a level adjacent said outlet and being connected to a conduit leading to a vent, a damper controlled by-pass between said outlet and conduit and adapted to be open so as to permitnatural draft operation of said combustion burner and the flow of flue gases through said outlet and by-pass to said vent and power driven means in said passageway for closing said by-pass and effecting a forced draft through said combustion burner, outlet and conduit to said vent, means for supplying fuel to said COIIlbllS. tion burner and means associated with said fuel supply means forrendering said power driven means operative and inoperative.

3. In combination with a space heater having a heater body with an oil burning combustion burner constructed and arranged to operate under natural draft therein and an outlet for the flue gases, air intake means for admitting air to said burner to support combustion, an econo-.

mizer having a passageway for said flue gases therethrough, one end of said passageway being connected to said outlet and the other end of said passageway being connected to a vent, means in said passageway for effecting a forced draft of saidflue gases from said combustion burner and through said passageway, a damper controlled by-pass around said forced draft effecting means arranged to be open when said forced draft efiecting means ar inoperative and to. be closed when said draft effecting means are operative, means for regulating the supply of fuel to said combustion burner, means actuated by said regulating means for rendering said forced draft effecting means operative and inoperative, and means for circulating a medium to be heated.

,over said economizer when said forced draft effecting means are operative, said economizer being arranged so as to be exposed to the medium to be heated on the discharge side of said circulating means.

s, In combination with a combustion burner asraivo heat exchange elements to a vent and lay-pass means for the flue gases between one of said heat exchange elements and a part of said conduit and arranged to be opened and closed in accordance with variations in draft pressure in said conduit during the operation of said burner, means arranged out of the path of how of the flue gases during the operation of said burner under natural draft for effecting a forced. draft through said combustion burner, heat exchange elements and conduit means when said by-pass is closed, means" for circulating a medium to be heated over the one of said heat exchange elements remote from said burner when said forced draft efiecting means are operative, said one of said heat exchange elements being arranged in the path of flow of the medium to be heated on the discharge side of said circulating means, and a single motor operatively connected to said forced draft effecting means and said circulating means'for simultaneously operating the same.

5. In combination with a space heater having a heater body with an atmospheric type of oil buming combustion burner constructed and arranged to operate on natural draft therein, air intake means for admitting air to said burner to support combustion, and an outlet for flue gases therefrom, an economizer having a passageway for flue gases therethrough, said space heater being arranged to deliver heat recovered from the flue gases independently of said economizer, means for effecting a forced draft of said flue gases from said combustion burner and through said passageway, a damper controlled by-pass around said forced draft effecting means arranged to be open when said forced draft effecting means are inoperative during operation of said burner and to be closed when said forced draft effecting means are operative, said forced draft effecting means comprising a, blower, a motor for driving said blower and another blower driven by said motor simultaneously with said first-mentioned blower and operative for circulating a medium to be heated over said economizer, said economizer being arranged in the path of flow of said medium to be heated on the discharge side of said other blower, and means for starting said motor when the fuel supply to said burner is increased.

6. An economizer unit adapted to be operatively arranged between the flue outlet of a combustion burner of a. space heater, furnace or the like, which is constructed and arranged to burn fuel under natural draft and an atmospheric vent for the flue gases therefrom, said economizer being arranged out of the path of flow of the air to be heated by said space heater, furnace or the like and comprising a radiator having a passageway for flue gases therethrough, one end of said passageway being adapted for connection to the flue outlet of said combustion burner and the other end of said passageway being connected to said vent, a by-pass short-circuiting a part of operative when said by-pass is closed for effecting a forced clrculationof air to be heated in heat exchange relationship with said radiator, said of said forced air cir- ,tion of said burner.'

. 10. Heating apparatus adapted to be operativemeans operative and inoperative during operaly arranged between theflue outlet of a. combustion burner, which is constructed and arranged to operate under natural draft, and an. atmospheric vent, said burner being provided with air passageway being-adapted for connection to a conduit leading to said vent, a by-pass shortcircuiting a part of said passageway and arranged to be opened and closed in accordance with variations in draft pressure in said part of said passageway, means for eflecting a forced circulation of air to be heated in heat exchange relationship with said radiator when said by-pass is closed, means in said partof said passageway adapted forefifecting the forced flow of flue gases therethroughand from said burner to said vent when said by-'pass is closed, said by-pass including a pivoted damper having a part thereof on onelside of said pivot exposed to the suction effect of said means for effecting the forced flow of flue gases through said passageway and having another part thereof on the other side of said damper exposed to the discharge side ofsaid means for effecting the flow of flue gases through said passageway, and a single motor operatively connected to both of said means for simultaneously operating the same. 1 a

8. In combination with a heat exchange element having acombustion burner which is constructed and arranged to operate under" natural draft conditions for supplying heated gases of combustion tosaid element, 'air intake means for admitting air to said burner to support combustion, said element being arranged to deliver heat recovered from the gases of combustion'by, the gravity circulation of air therefrom said outlet of said heat exchange element to an atmospheric vent and including a radiator through which gases of combustion may flow, said radiator being out of the-path of gravity intakemeans for admitting air to said burner to support combustion, said heating apparatus [comprising a heat exchange element, means in- I eluding said element providing a flue gas passageway between said outlet and said vent, a bypass short-circuiting a part of said passageway,

blower means operable for effecting a forced circulation of air to be heated in heat exchange relationship with said element only when said bypass is closed, blower means insaid part of said passageway operable for effecting the forced flow of flue gases through said passageway and from said burner outlet to said vent when said by-pass is closed, said by-pass including a damper, means automatically positioningsaid damper to open said by-pass upon stoppage of said flue gas blower means, and a single electric motor having a shaft, said blower means having co-axially arranged fans directly connected to said motor shaft to be simultaneously driven thereby.

11. Heating apparatus adapted to be operatively arranged between the flue outlet of a combustion burner, which is constructed and arranged to operate under natural draft, and an atmospheric vent, said burner being provided with air intake means for admitting air to said burner to support combustion, said heating apparatus comprisin a heat exchange element, means including said element providing a flue gas paspass short-circuiting apart of said passageway,

sageway between said outlet and said vent, a byblower means operable for. effecting a forced circulation of air to be heated in heat exchange relationship with said element only when said by-pass is closed, blower means in said part of said passageway operable for effecting the forced flow of flue gases through said passageway and from, said burner outlet to said'vent when said by-pa-ss is closed, said by-pass including a -damper, means automatically positioning said flow of air over said heat exchange element, elec- I trio power operated means for effecting a forced draft of the gases of combustion through said combustionburner, heat exchange element and outlet therefrom, conduit and radiator, and means operable in response to failure of the electric power for said draft effecting means for shunting said radiator out of said conduit, without stopping the flow "of combustion gases under natural draft from said burner through said heat exchangeelement to said vent.

9. In combination with a heat exchange ele ment having a combustion burner which is constructed and arranged to supply heated flue gases thereto under natural draft conditions and a conduit for the flue gases between the outlet from said element and an atmospheric vent, air intake means for admitting air to said burner to support combustion, electric power operated means for effecting a forced draft through said combustion bumer and conduit to said vent, a bypass around said means arranged to be open when said means are inoperative due to-power failure, to permit operation of said burner under natural draft conditions, means for supplying fuel to said combustion burner and means actuated by an adjustment of said fuel supplying means for renderin said forced draft effecting damper to open said by-pass upon stoppage of said flue gas blower means, and electric motor means operatively connected to said blower means for operating the same, the supply of fuel to said combustion burner being independent of the cur rent supply for said motor means so that in the event of failure of the current supply, said burner will continue to operate and said by-pass will be opened 'to permit natural draft operation of said burner. I

12. Heating apparatus comprising a hollow member provided with a gas inlet opening and a gas outlet opening, partition means defining a path between said inlet and outlet openings,

said partition means having a damper-controlled opening therein providing a by-pass around part i of said path, and a blower arranged insaid part of said path and operative for effecting the forced flow of gas through said member when said bypass is closed, a combustion burner adapted to permit natural draft operation of said burner when said by-pass is open, and means operable with said blower for circulating air to be heated over said hollow member.

' 13. Heating apparatus comprising a hollow member provided with a gas inlet opening and a gas outl-ei'ropening, partition means defining a path between said inlet and outlet openings, said partition means having a damper-controlled opening therein providing a by-pass around part of said path, and a blower arranged in said part of said path and operative for effecting the forced flow of gas through said member when said bypass is closed, a combustion burner adapted to burn fuel under natural draft operation and provided with an air intake opening and a combustion products outlet opening, said gas inlet opening of said hollow member being connected to said combustion products outlet opening of said burner so as to effect forced draft operation of said burner when said by-pass is closed and to permit natural draft operation of said burner when said by-pass is open, and means operable with said blower for circulating air to be heated over'said hollow member, said blower and air circulating means being driven by an electric motor, means forsupplying fuel to said burner and including a manually operable device for adsaid forced draft effecting means and in by-passclosed position during the operation of said forced draft effecting means so that during operation of said burner said by-pass is open when said forced draft means are inoperative and closed when said draft effecting means are, operative, manually operable means for regulating the supply of fuel to said combustion burner and means actuated by said regulating means for rendering said forced draft effecting means operative and inoperative, said economizer being arranged out of the path of flow of air over said heater body.

16. In combination with a combustion burner constructed and arranged to operate under natural draft, air intake means for admitting air to said burner to support combustion, control means for regulating the operation of said combustion burner. to provide for high or low fire operation thereof, a pair of heat exchange elements connected to said combustion burner so as to receive justing the rate of fuel feed and a circuit for supplying current to said motor for operating the same and including a switch which is open and closed by operation of said device.

14. In combination with a space heater havin a heater body with an oil burning combustion burner constructed and arranged to operate under natural draft therein and an outlet-for the flue gases, air intake means for admitting air to said burner to support combustion, a path for flow of air in heat exchange relationship with said heater body, an economizer having a passageway for said flue gases therethrough, one

. end ofsaid passageway being connected to said .outlet and the other end of said passageway being connected to an atmospheric vent, means in said passageway for effecting a forced draft of said flue gases through said combustion burner and passageway, a damper controlled by-pass around said forced draft eflecting means, means automatically positioning the damper of said bypass in by-pass-open position upon the stoppa e of said forced draft effecting means and in bypass-closed position during the-operation of said forced draft effecting means so that during operation of said burner said by-pass is open when said forced draft means are inoperative and closed when said draft effecting means are operative, said econom'izer' being arranged out of the path of flow of air over said heater body.

} 15. In combination with a space heater having a heater body, with an oil. burning combustion burner constructed and arranged to operate unthe heated flue gases therefrom, conduit means for conducting said flue gases from said heat exchange elements to a vent, means for preventing the flow of said heated flue gases through one of said heat exchange elements during operation of said burner without interfering with the flow under naturaldraft of the flue gases from said combustion burner and through said other one of said heat exchange elements and said conduitmeans to saidvent, and blower means for effecting a forced draft from said combustion burner and throughsaid heat exchange elements and conduit means and operative for rendering said preventing means inoperative, and blower control means operative, upon regulating the operation by said control means of said burner to provide for low fire operation thereof, to concurrently discontinue operation of said blower means.

17. In eombinatidn with a heat exchange element having a combustion burner constructed and arranged to operate under natural draft operatively associated therewith and an outlet for the flue gases, air intake means for admitting air to said burner to support combustion, control means for regulating the operation of said combustion burner to provide for high or low fire operation thereof, a conduit connected to said outlet and leading to a vent for saidflue gases, blower means for effecting a forced draft through said-combustion burner and conduit and a damp.-

der'natural draft therein and an outlet for the flue gases, air intake means for admitting air to said burner to support combustion a path for flow of air in heat exchange relationship with said heater. body, an economizer having a pas.-

sageway for said flue gases therethrough, one end of said passageway being connected to said outlet and the other end of said passagewaybeing connected to a vent, means in said passageway for effecting a forced draft of said flue gases from er controlled by-pass around said forced draft efl'ecting means, blower means automatically positioning the damper of said by-pass in by-passopen position uiion the stoppage of." said blower means and in by-pass-closed position during the operation of said'blower means so that during operation of said burner said 'by-pass is open when said blower means are inoperative so as to permit natural draft operation of 'saidbumer and flow of flue gases through said heat exchange element and-conduit at such time, and

I blower control means operative, upon regulating the operation by said control means of said burner "to 'providefor low fire operation thereof, to: concurrently discontinue operation of said blower means.

said combustion bumer and through said pas-LL sagewayfa damper controlled by-pass around said forced draft effecting. means, means automatically positioning the damper of said by-pass in by-pass-open positiontupon the ranged to supply heated flue gases thereto under stoppage of 18. In co" bination with a heat exchange element having a combustion burner operatively associated therewith which is constructed and arnatural-jdraft conditions for heating-the same and outlet for the flue gases, said burner being provided with air intake means for -admitting flue gases therethrough, power driven blower means for effecting a forced draft through said combustion burner, outlet, passageway and conduit to said vent, a damper controlled by-pass around said forced draft effecting means, means automatically positioning the damper. of said bypass in by-pass-open position upon the stoppage of said forced draft efiecting means and in bypass-closed position during the operation of said forced draft effecting means so that during operation of said burner said by-pass is open when said means'are inoperative, blower control means operative, upon regulating the fuel supplied by said fuel supplying means to said combustion burner to provide for low fire operation thereof, to concurrently discontinue operation of said blower means, and means associated with said power driven means for circulating a medium to be heated in heat exchange relationship with said radiator when said power driven means are operative.-

19. An economizer unit adapted to be 'oper-' atively arranged between the flue outlet of a combustion burner of a heating element which is con-- 7 effecting means, means operable without regard to the operativeness of said electric motor driven meansor the current supply therefor for controlling? the heat output of said combustion burner; .1

21-." In 'combination with a space heater having a heater body with an atmospheric type of oil burning combustion burner constructed and arranged to operate on natural draft therein and air intake means for admitting air to said burner to support combustion, and an outlet for flue gases therefrom, an economizer having a passageway for flue gases therethrough, said space heater being arranged to deliver heat recovered from the flue gases independently of said eoonomizer, means for effecting a forced draft of said flue gases through'said combustion burner and passageway, a damper controlled by-pass around I said forced draft eflecting means adapted to be open when said forcedd'raft effecting means are inoperative during operation of said burner and to be closed when said forced :draft effecting means are operative, means forautomatically opening said by-pass upon stoppage of said forced draft effecting means and for automatically closing said by-pass during operation of said forced structed and arranged to burn fuel under natural draft and an atmospheric vent for the flue gases therefrom, a path for flow of air in heat exchange relationshipwith said heating element, said economizer being arranged out of the path of flow of the air to be heated by said heating element and comprising a radiator having a passageway for flue gases therethrough, one end of said passageway being adapted for connection to the flue outlet of said combustion burner and the other end of said passageway being connected to said vent, a Dy-pass short-circuiting a part of said passageway and arranged to be opened and closed during operation of said combustion burner, means in said part of said passageway adapted for effecting the forced flow of flue gases therethrough and from said burner to said vent when said by-pass is closed, means for automatically opening said by-pass upon stoppage of said forced draft effecting means and for automatically closing saidlay-pass during operation of said forced draft effecting means, means for circulating air to be heated in heat exchange relationship with said radiator'when said forced draft effecting means are operating, and a single motor operatively connected to both of said means for simultaneously operating the same, said radiator being arranged in the path of flow of air on the discharge side of said air circulating means.

20. In combination withiacombustion burner constructed and arranged to operate under natural draft and having air intake means for admitting air to said burner to support combustion, a conduit for the flue gases between the outlet from said burner and the vent, electric mctor draft effecting means, said forced draft efiecting means comprising a blower, a motor for driving said blower and another blower driven by said motor simultaneously with said first-mentioned blower and operative for circulating a medium to be heated over said 'economizer, said economizer being arranged in the path of flow of said medium to be heated on the discharge side of said other blower.

22. In combination with a space heater comprising a heat exchange element having a combustion burner which is constructed and arranged to'operate under natural draft for supplying heated flue gases thereto and an outlet for flue gases,-air intake means for admitting air to said burner to support combustion, regulatable means for supplying fuel to said combustion burner to provide for high or low flre operation thereof, said heat exchange element being exposed to a heat transfer medium which is free to circulate said conduit and arranged so as to be open to permit natural draft operation of said burner and the flow of the flue gases from said combustion burner to said vent, blower means for efconduit to said vent, and-a by-pass around said means adapted to be open during operation of said burner when said means are inoperative and in eventof failure of said means to operate, due to' current failure or otherwise so as to permit continued operation of said burner under natural draft, means for automatically opening said by-pass upon stoppage of said forced draft effecting means and for automatically closing said by-pass during operation of said forced draft fecting a forced draft through said combustion burner, connection, radiator and conduit to said vent and operative for closing said :by-pass during, high fire operation of said combustion burner, and blower control means operative, upon-regulating the fuel supplied by said fuel supplying means to said combustion burner to provide for,

low fire operation thereof, to concurrently discontinue operation of saidblower means.

23. In combination with a heat exchange element having a combustion burner which is 'constructed and arranged to supply heated flue gases thereto under natural draft conditions for heating the same and an outlet for the-flue gases, air

intake means for admitting air to said burner to support combustion, regulatable means forsupplying fuel to said combustion burner to provide for high or low fire operation thereof, a radiator ing a passageway for flue gases therethrough, one end of said passageway being connectedto said outlet and the other end of said passageway terminating at a level adjacent said outlet and being connected to a conduit leading to a vent, a; damper controlled by-pass between said outlet and conduit and adapted to be open so as to permit natural draft operation of said combustion burner, and the flow of flue gases through said outlet and by-pass to said vent, power driven means for closing said by-pass and including a blower for effecting a forced draft through said combustion burner, outlet and conduit to said vent during high fire operation of said combustion burner, and blower control means operativaupon regulating the fuel supplied by said fuel supplying means to said combustion burner to provide for low fire operation thereof, to concurrently discontinue operation of said blower means.

pass around said blower means, said valve controlled by-pass being constructed and arranged so as to be closed whensaid blower means are operative and to be open during operation of aid burner when said blower means are inoperative so as to permit operation of said burner under natural draft, means operable simultaneously with said blower means for utilizing the heat exchange surface of said radiator for effecting the transfer of heat to a medium to be heated, and blower control means operative, upon regulating the fuel supplied by said fuel supplying means to said combustion burner to provide for low fire operation thereof, to concurrently discontinue operation of said blower means.

25. In combination with a combustion burner constructed and arranged to operate under natural draft and having air intake means for ad- 2a. In combination with a heat exchange ele- V ment having a combustion burner which is constructed and arranged to operate under natural draft operatively associated therewith and through which the hotgases of combustion from said burner pass, said burner being provided with air intake means for admitting air to said burner to support combustion, regulatable means for supplying fuel to said combustion burner to provide for high or low fire operation thereof, a conduit for conducting the hot gases of combustion from said heat exchange element to a vent, a radiator having a passageway therethrough and operatively connected to said conduit, blower means for efiecting a forced draft through said combustion burner, heat exchange element, conduit, and radiator during high fire operation of mid combustion burner, a valve controlled bymitting air to said burner to support combustion, control means for regulating the operation of said combustion burner to provide for high or low fire operation thereof, a conduit for the flue gases between the outlet from said combustion burner and an atmospheric vent, electric power driven'blower means for effecting a forced draft through said combustion burner and conduit during' high fire operation of said burner, a by-pass around said blower means adapted to be opened when said blower means are inoperative so as to permit natural draft operation of said burner in the event of power failure, means for automatically opening said by-pass upon stoppage of said electric power driven means, and blower control means operative, upon regulating the operation by said control means of said burner to provide for low fire operation thereof, to concurrently discontinue operation of said blower means.

MORITZ L. MUELLER. 

